The present invention concerns a metal seal plug and, particularly, a metal seal plug for use in sealing off a tubing run in an underwater oil and/or gas well system.
The improved plug of the present invention utilizes a metal-to-metal seal which provides a reliable, wire line or tubing installable and retrievable, plug for subsea tubings. A metal-to-metal type seal has superior seal reliability over conventional, resilient, elastomer type seals. Materials chosen for the metal seals are less susceptible to failure and resultant leaks than available elastomer materials. Elastomer seal systems are susceptible to deterioration due to age, gas infusion, cold flow or creep. When used in subsea christmas trees the improved plug is run after completion work has been accomplished and before the completion riser is retrieved. When employed in this manner, the plug is less costly and provides a more reliable pressure seal and a more reliable means of closing and opening tubings than hydraulically actuated valves or plugs which use only resilient seals.